The present invention relates generally to closures for flowable material containers and more particularly closure assemblies for medical fluid containers.
It is common medical practice to provide fluids to a patient either intravenously or enterally as a method of treating a patient for various medical conditions. Frequently, the fluids to be administered to a patient are contained in a flexible container. One method of forming a flexible container is to seal two sheets of flexible material about the periphery of the sheets to create a fluid tight chamber. A port tube assembly is frequently placed between the sheets during the sealing process to create a communication between the fluid chamber and the exterior of the container to provide a means of introducing fluid into or dispensing fluid from the container. The port tube assembly typically includes an outer port tube that attaches to the sidewalls of the container and a second tube called a membrane tube that is disposed coaxially within the port tube. The membrane tube has a membrane or diaphragm that seals the port tube assembly. The membrane is typically punctured by a spike of a fluid administration set to place the contents of the container in fluid communication with a patient.
Port tubes and membrane tubes are fabricated from monolayer or multiple layered materials. The port tube typically has an inner layer of polyvinyl chloride and the membrane tube has an outer layer of PVC. To assemble the port tube assembly, the membrane tube is dipped in cyclohexanone or other suitable solvent and is inserted in a telescoping fashion into the port tube. The solvent melts the PVC of both the port tube and the membrane tube thereby hermetically sealing the membrane tube to the port tube.
There has been a great effort by many manufacturers of medical articles to replace PVC materials with non-PVC containing materials. Flexible PVC containers include low molecular weight additives know as plasticizers which may exude into the solutions contained in the container. U.S. Pat. Nos. 5,998,019 and 5,849,843, which are incorporated herein by reference and made a part hereof, disclose replacing PVC materials in medical fluid containers with non-PVC containing materials.
U.S. Pat. No. 5,356,709, assigned to the same assignee of the present invention, discloses a non-PVC coextruded medical grade port tubing. The tubing has an outer layer of a blend of polypropylene and SEBS a tie layer and a core layer of a blend of polyamide and EVA.
U.S. Pat. No. 5,533,992, assigned to the same assignee of the present invention, discloses a non-PVC material for fabricating medical tubings and medical containers. Polymer blends for fabricating medical tubing disclosed in the ""992 patent include polyurethane blended with one or more of the following: EVA, SEBS, PCCE, and thermoplastic copolyester elastomers.
The present assignee is presently marketing a container for storing, shipping and delivering of medical fluids. A port tube provided with the container has an outer layer of a polymer blend by weight of the following four components: 40% polypropylene, 40% ultra low density polyethylene, 10% dimer fatty acid polymamide and 10% styrene-ethylene-butene-styrene block copolymer with maleic anhydride functionality. The port tubing has an inner layer of PVC for solvent bonding to a membrane tube of PVC material.
The present invention provides a non-PVC port tube, a non-PVC membrane tube and a non-PVC closure assembly for use in flowable material containers such as medical and food containers.
The closure assembly includes a port tube and a membrane tube coaxially mounted therein. The port tube has a first layer and a second layer disposed coaxially within the first layer. In a preferred form of the invention the first layer is capable of being sealed to sidewalls of a flowable materials container and more preferably using radio frequency sealing techniques. In a preferred form of the invention the first layer is a polymer blend of four components. The first component is present in an amount by weight of from about 25% to about 50% by weight of the first layer. The first component is a first polyolefin of a propylene containing polymer. The second component is present in an amount by weight of from about 0 to about 50% by weight of the first layer and is a second polyolefin. The second polyolefin is an xcex1-olefin containing polymer and in a preferred form of the invention is an ethylene and xcex1-olefin copolymer. The third component is present in an amount by weight of from about 0% to about 40% by weight of the first layer and is a radio frequency (xe2x80x9cRFxe2x80x9d) susceptible. The RF polymer is selected from the group consisting of polyamides, ethylene acrylic acid copolymers, ethylene methacrylic acid copolymers, polyimides, polyurethanes, polyesters, polyureas, ethylene vinyl acetate copolymers with a vinyl acetate comonomer content from 18-50% by weight of the copolymer, ethylene methyl acrylate copolymers with methyl acrylate comonomer content from 18%-40% by weight of the copolymer, ethylene vinyl alcohol with vinyl alcohol comonomer content from 15%-70% by mole percent of the copolymer; and (4) from about 0% to about 40% of a first thermoplastic elastomer. Particularly suitable blends are disclosed in greater detail in U.S. Pat. No. 5,686,527 which is incorporated herein by reference and made a part hereof.
The second layer of the port tube is disposed coaxially within the first layer and is a non-PVC material that is reactive with an organic solvent. More preferably the second layer is reactive with an aromatic solvent including cyclohexanone, toluene, tetrahydofuran, cumene, xylenes, diethyl benzene decalin, tetralin and amyl benzene to name a few. In a preferred form of the invention the second layer is a blend of from about 25% to about 55% by weight of a thermoplastic elastomer, 20% to about 45% of a polyester polyether block copolymer, 0%-15% ethylene vinyl acetate, 0-10% of a propylene containing polymer and from 0%-35% of a polymer selected from the group consisting of acrylonitrile butadiene styrene block copolymer, styrene ethylene butene copolymer, styrene acrylonitrile copolymer and cyclic olefin or bridged polycylic olefin containing polymers.
In one preferred form of the invention, the membrane tube has two layers an outer layer and an inner layer disposed coaxially within the outer layer. The outer layer is reactive to organic solvents and more preferably the aromatic solvents identified above. The outer layer of the membrane tube is of a material selected from the same materials as the second layer of the port tube. Likewise, the inner layer of the membrane tube is capable of being sealed using radio frequency sealing techniques and is selected from the same materials as set forth above for the first layer of the port tube.
The present invention also provides for membrane tubings having more than two layers, such as three layers or more. In a preferred embodiment a core layer of a thermoplastic elastomer such as a styrene and diene type copolymer such as Kraton KG 2705 sold by Shell Chemical Co.